This invention relates to a dual-energy hot water supply system. In a more specific embodiment, the invention relates to an economically-operated, dual-energy hot water supply system and its operating method.
In the past few years, hot water supply systems combine gas water heaters and heat pump water heaters. For example, Chinese patent application no. 200820202823.2 discloses a heat pump water heater with a gas auxiliary heating unit. The system includes a confined water tank, a control device, and outlet piping. The mentioned gas auxiliary heating unit is installed in series with the outlet piping of the confined water tank. The downdraft temperature probe, water flow sensor, and gas control valve are connected to the control unit respectively. The system is characterized by compensating the heat pump effectively in the insufficient heat supply conditions and expanding the applicable areas of the heat pump water heater. For another example, Chinese patent application no. 200920300786.3 discloses a solar water heater with two auxiliary heating methods, i.e. a heat pump water heater and a gas water heater. The system integrates the advantages of the gas water heater and heat pump water heater, and avoids their disadvantages.